Sampled - Data Modeling and Analysis of PWM DC - DC

The power stage of the PWM DC-DC converter is modeled and analyzed using the sampleddata approach. This work complements the companion paper [1] which develops sampled-data models and analysis for the closed-loop converter. Separate models for the power stage are essential for controller design. The work addresses continuous and discontinuous conduction mode under voltage mode control, and continuous conduction mode under current mode control. For each configuration, nonlinear and linearized sampled-data models, and control-to-output transfer function are derived. Use of these models for controller design is illustrated. In addition, a new continuous-time switching frequency-dependent model of the power stage is derived from the sampled-data model. Examples illustrate the increased accuracy of control design using the new power stage models.